This invention relates, in general, to semiconductor devices and, more particularly, to ball-grid array semiconductor devices.
Ball Grid Array (BGA) and Over-Molded Pad Array Carrier (OMPAC) semiconductor devices have been developed to improve both the electrical and thermal performance characteristics of surface mount semiconductor devices. Typically, BGA and OMPAC semiconductor devices include a thin Printed Circuit Board (PCB) substrate on which a semiconductor chip is mounted. Portions of the chip are electrically coupled to conductive traces formed on a top surface of the PCB. Each conductive trace is routed to a corresponding conductive trace on the bottom surface of the PCB by a conductive via which extends through the PCB. The traces on the bottom surface of the PCB each terminate at a conductive pad to form an array of pads on the bottom of the PCB. The semiconductor chip and a portion of the PCB are encapsulated by an opaque mold compound using conventional molding techniques.
Although BGA and OMPAC semiconductor devices offer the advantages of increased interconnect packaging densities, elimination of coplanarity and skew limitations, low lead inductance, and a low profile, these devices have been unsuitable for use in optical applications because of the opaque mold compound.
Accordingly, it would be advantageous to have BGA and OMPAC devices capable of sending and receiving optical signals. It would be of further advantage for the BGA and OMPAC devices to be cost effective without reducing their electrical and thermal characteristics.